The method of spines is the simplest remeshing rule in Ansys Polyflow. Mesh nodes are organized along lines of remeshing, called spines. This method is available only for 2D flows, since its applicability in 3D would be very limited from a geometric point of view. Spines are collections of nodes logically arranged in a one-dimensional manner. They are obtained by slicing up the 2D domain. The slicing process is performed in a direction that is topologically normal to the free surface or moving interface, and therefore the definition of initial and final spines is required.
Spines are connected lines (which are not necessarily straight) and have boundary
nodes at each extremity. Consider a spine characterized by extremities 
and 
. With the spine remeshing rule, the displacement of an internal mesh
node 
on this spine is defined as follows:
 | (16–1) |
where 
is the variation of position and
 | (16–2) |
 | (16–3) |
The spine remeshing technique is illustrated in Figure 16.2: The Method of Spines, which shows the original and deformed mesh configurations.
The spine technique does not remesh tangentially along free surfaces and moving interfaces. In view of its low requirements of computer resources, it is well adapted to a large class of 2D problems with jet-like free surfaces and moving interfaces.
See User Inputs for Remeshing for information about using the method of spines.